Spinning solution comprising acrylonitrile polymer in glycolic acid nitrile and ethylene chlorohydrin, and process for making



Vereinigte Glanzstoff-Fahriken AG, Wuppertal-Elberfeld, Germany No Drawing. Filed July 6, 1956, Ser. No. 596,152 Claims priority, application Germany July 8, 1955 11 #Ciairns. (ill. l)32.4)

This invention relates to a novel solvent for poly acrylonitrile and mixed polymers of polyacrylonitrile. The invention further relates to a spinning solution and improved process for spinning artificial filaments, and more particularly for spinning filaments, threads, fibers or the like, of polyacrylonitrile or mixed polymers of polyacrylonitrile from a spinning solution containing the polymer dissolved therein.

In order to spin filaments of polyacrylonitrile or its mixed or hetero-polymers, it is necessary that the polymeric substance first be dissolved in a solvent to provide a spinning solution. The discovery of suitable solvents for polyacrylonitrile and its mixed polymers has been a difiicult problem in the art since it is very diflicult to predict the suitability of any proposed solvent.

It is known that polyacrylonitrile or its mixed polymers will dissolve in glycolic acid nitrile to form a spinning solution from which artificial filaments can be spun. It has been proved, however, that a spinning solution of polyacrylonitrile in glycolic acid nitrile has several disadvantages in the results obtained when spinning artificial filaments. A sticky or tacky formation is ofttn ob served in the use of these spinning solutions, this sticki ness having an adverse eifect upon the spinning process and a consequent impairment of the quality of the threads or filaments being produced. Another disadvantage in the use of glycolic acid nitrile as a solvent is that at higher temperatures, the glycolic acid nitrile tends to decompose and thus has a deleterious effect upon the spinning of filaments. The addition of nitromethane or aliphatic diesters to the glycolic acid nitrile solvent has been attempted but does not provide any substantial improvement in the properties of the spinning solution as regards its stability against decomposition and its tendency toward stickiness. Also, if glycolic acid nitrile is used alone as the solvent for polyacrylonitrile, it is particularly diflicult to favorably and satisfactorily develop the thread or filament in a subsequent wet-spinning process.

One object of the present invention is to provide a novel and effective solvent for poly'aorylonitrile and mixed polymeers of polyacrylonitrile.

Another object of the invention is to provide a novel spinning solution for spinning artificial filaments of polyacrylonitrile or its mixed polymers.

Still another object of the invention is to provide an improved process for spinning artificial filaments of polyacrylonitrile or its mixed polymers.

Yet another object of the invention is to provide a solvent for the purpose described whereby the disadvantages of stickiness or tackiness can be avoided.

Another object of the invention is to provide a solvent or spinning solution which is stable against decomposition.

Another object of the invention is to provide artificial filaments of polyacrylonitrile or its mixed polymers which have improved textile or fiber properties and characteristics, including an especially good color stability.

These and other objects and advantages of the inven- 7 tion will become more apparent upon a consideration of the following description.

tent

It has now been found in accordance with the invention that a perfect spinning solution of polyacrylonitrile or its mixed polymer is obtained by dissolving the polymeric substance in a solvent mixture of glycolic acid nitrile and ethylene chlorohydrin. Glycolic acid nitrile is a well known and readily obtainable solvent, sometimes named methylene cyanohydrin, formaldehyde cyanohydrin, or hydroxy methyl cyanide. Ethlyene chlorohydrin is likewise readily obtainable under various other names such as chloroethyl alcohol, 2-chloroethyl alcohol, and l-hydroxy-Z-chloroethane. Glycolic acid nitrile can be prepared from formalin (-40%) to which there are added equimolecular quantities of hydrocyanic acid (see Beilsteins Handbuch de Organischen Chemie, 4th edition,

page 242).

The solvent mixture preferably consists of these two compounds or components in proportions of about 60 to 95% by Weight of glycolic acid nitrile and about 405% by weight of ethylene chlorohydrin. The most effective proportion is obtained in a mixture preferably containing about 35 to 25% by weight of ethylene chlorohydrin and a corresponding proportion of about 65 to by weight of glycolic acid nitrile. With this relatively high proportion of ethylene chlorohydrin in the solvent mixture, the glycolic acid nitrile is fully stabilized against decomposition. However, small proportions of ethylene chlorohydrin down to about 5% by weight also stabilizes the glycolic acid nitrile to a considerable extent.

An excellent color stability of the polyacrylohitrile or modified polyacrylonitrile is achieved if a solvent-reducing substance, i.e., a suitable reducing agent, is added to the solvent or spinning solution. Only a small quantity of a reducing agent, such as sulfur dioxide or a formaldehyde, is necessary and is preferably added to the solvent mixture before dissolution of the polymer therein. Generally, the quantity of reducing agent required is less than 1% by weight of the solvent mixture, the exact quantity being readily determined by routine experimentation. Tht solvent mixture or spinning solution to which such a reducing agent has been added and the threads spun from the solution are distinguished by a very bright color which fails to darken even after a considerable period of heating. Other suitable reducing agents include paraformald-ehyde, hydroxylamine, alkali metal-hydrosulfite, rongalite.

The novel glycolic acid nitrile-ethylene chlorohydrin solvent is particularly adapted to the formation of spinning solutions of polyacrylonitrile. However, the solvent is also eifectively utilized with a modified polyacrylonitrile such as is obtained by a copolymerization with various other monomeric compounds such as methyl methacrylate, acrylic acid amides, methacrylate, vinyl pyridine, and vinyl carbazole.

Such copolymerization results in mixed polymers or hetero-polymers of polyacrylonitrile which have about the same characteristics as polyacrylonitrile itself, particularly where the acrylonitrile monomer forms a major proportion of the mixed polymer. The solvent and spinning solution of the invention is preferably applicable to those mixed polymers of acrylonitrile in which the proportion of acrylonitrile is at least by weight.

The use of the solvent mixture of the invention provides a spinning solution of polyacrylonitrile or its mixed polymers which neither tends to become sticky or tacky nor shows signs of decomposition. The spinning of polyacrylonitrile proceeds more perfectly than has heretofore been possible. Furthermore, the threads or spun filaments can be finished either by the dry-spinning process or by 0 the wet-spinning process, and the finished thread is well developed with uniform physical and chemical properties, particularly for use in the textile industry.

The invention is further illustrated by the following examples but is not limited to these examples. The proportions or quantities of the various materials employed are stated in parts by weight unless otherwise indicated.

Example 1 1.8 kilograms of polyacrylonitrile (K value about 95) and 8.2 kilograms of a solvent mixture consisting of 70% by weight of glycolic acid nitrile and 30% by weight of ethylene chlorohydrin are mixed together at a temperature of about 15 C. to 20 C. The resulting solution is concurrently deaerated. The fully deaerated mixture, while being constantly stirred, is gradually brought to a temperature of about 110 C. to 115 C. and kept at this temperature for approximately one hour. A very brilliant spinning solution forms which is then filtered and spun by the dry-spinning process. The resulting threads after being stretched 1000% have a strength of 4.4 grams per denier with an elongation at break of 11 to 12%. After the co-called thermo-fixing of the stretched or drawn threads, the strength increases to from 4.8 to 5.0 grams per denier and the elongation at break rises to from 20 to 25%.

Example 2 A spinning solution is formed as described in Example 1, except, however, that sulfur dioxide is introduced into the solvent mixture before the formation of the spinning solution. Sufiicient sulfur dioxide is introduced to give a pH value of about 3. The spinning solution is now spun through a multiple-hole nozzle or spinneret at approximately room temperature into a precipitating bath 4 meters in length which is filled with 80% technical xylol and 20% butanol. The spinning speed or drawing off of the threads is about 70 meters per minute. The resulting bundle of thread is squeezed through a mangle, wound in the customary manner, and then stretched or drawn. With a 900% stretch and subsequent thermo-fixing at 125 C. for a period of 30 minutes, the thread has a strength of approximately 4.7 grams per denier with an elongation at break of 22 to 25%.

Example 3 1.6 kilograms of a modified polyacrylonitrile (K value about 100), which is formed by copolymerizing 94% of acrylonitrile and 6% methyl methacrylate, are dissolved at 110 C. to 115 C. corresponding to the data in Example l, with 8.4 kilograms of a solvent mixture consisting of 65% by weight of glycolic acid nitrile and 35% by weight of ethylene chlorohydrin, 0.5% of paraformaldehyde being added (with reference to the quantity of the solvent mixture). The solution is filtered and spun as in Example 2. After stretching and thermo-fixing, threads are obtained which are well adapted to dyeing and which have a very soft handle.

The invention is hereby claimed as follows:

1. A solution for spinning artificial filaments comprising a polymer of the group consisting of polyacrylonitrile and copolymers of acrylonitrile containing at least 85% by weight of acrylonitrile and another monomer selected from the group consisting of methyl methacrylate, acrylic acid amides, methyl acrylate, vinyl pyridine and vinyl carbazole dissolved in a mixture of about 60 to 95 per cent by weight of glycolic acid nitrile and about 40 to percent by weight of ethylene chlorohydrin.

2. A solution for spinning artificial filaments comprising a polymer of the group consisting of polyacrylonitrile and copolymers of acrylonitrile containing at least 85% by weight of acrylonitrile and another monomer selected from the group consisting of methyl methacrylate, acrylic acid amides, methyl acrylate, vinyl pyridine and vinyl carbazole dissolved in a mixture of about 60 to 95 percent by weight of glycolic acid nitrile and about 40 to 5 percent by weight of ethylene chlorohydrin, said mixture also containing less than about 1% by weight of a reducing agent.

3. A solution for spinning artificial filaments comprising polyacrylonitrile dissolved in a mixture of about 60 to 95 percent by weight of glycolic acid nitrile and about 40 to 5 percent by weight of ethylene chlorohydrin, said mixture also containing less than about 1% by weight of sulfur dioxide.

4. A solution for spinning artificial filaments comprising a copolymer of acrylonitrile and methyl methacrylate dissolved in a mixture of about 60 to 95 percent by weight of glycolic acid nitrile and about 40 to 5 percent by weight of ethylene chlorohydrin, said mixture also containing less than about 1% by weight of said solution of paraformaldehyde.

5. In a process for spinning filaments of a polymer of the group consisting of polyacrylonitrile and copolymers of acrylonitrile containing at least by weight of acrylonitrile and another monomer selected from the group consisting of methyl methacrylate, acrylic acid amides, methyl acrylate, vinyl pyridine and vinyl carbazole from a spinning solution containing said polymer dissolved therein, the improvement comprising adding less than about 1 by weight of a reducing agent to a mixture of about 60 to by weight of glycolic acid nitrile and about 40 to 5% by weight of ethylene chlorohydrin, and subsequently dissolving said polymer in said mixture.

6. In a process for spinning filaments of a polymer selected from the group consisting of polyacrylonitrile and copolymers of acrylonitrile containing at least 85% by weight of acrylonitrile and another monomer selected from the group consisting of methyl methacrylate, acrylic acid amides, methyl acrylate, vinyl pyridine and vinyl carbazole from a spinning solution containing said polymer dissolved therein, the improvement comprising adding less than about 1% by weight of a reducing agent selected from the group consisting of sulfur dioxide, formaldehyde, paraformaldehyde, hydroxylamine, alkali metal-hydrosulfite, and rongalite, to a mixture of about 60 to 95% by weight of glycolic acid nitrile and about 40 to 5% of ethylene chlorohydrin, and subsequently dissolving said polymer in said mixture.

7. The process as claimed in claim 6 wherein the reducing agent is sulfur dioxide.

8. The process as claimed in claim 6 wherein the reducing agent is paraformaldehyde.

9. A solution for spinning artificial filaments comprising a polymer of the group consisting of polyacrylonitrile and copolymers of acrylonitrile containing at least 85% by Weight of acrylonitrile and another monomer selected from the group consisting of methyl methacrylate, acrylic acid amides, methyl acrylate, vinyl pyridine and vinyl carbazole dissolved in a mixture of about 65 to 75 percent by weight of glycolic acid nitrile and about 35 to 25 percent by weight of ethylene chlorohydrin.

10. A solution for spinning artificial filaments as claimed in claim 9 containing less than about 1% by weight of a reducing agent.

11. In a process for spinning filaments of a polymer of the group consisting of polyacrylonitrile and copolymers of acrylonitrile containing at least 85% by weight of acrylonitrile and another monomer selected from the group consisting of methyl methacrylate, acrylic acid amides, methyl acrylate, vinyl pyridine and vinyl carbazole from a spinning solution containing said polymer dissolved therein, the improvement comprising dissolving said polymer in a mixture of about 65 to 75 percent by weight of glycolic acid nitrile and about 35 to 25 percent by weight of ethylene chlorohydrin.

References Cited in the file of this patent UNITED STATES PATENTS 2,843,558 Fujisaki et a1 July 15, 1958 FOREIGN PATENTS 694,827 Great Britain July 29, 1953 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent o. 3 OO9 894 Y November 21 1961 l Ernst Pirot It is hereby certified that error appears in the above numbered pat ent requiring correction and that the said Letters Patent should read as corrected below.

Column 1 line 39 for "'ofttn" read often line 52 for "'polymeers read polymers column 2 line l2 for "formalin" read formaline line 39 for "Tht read The column 3 line 2O for co-called read s0-called Signed'and sealed this 1st day of May 1962a (SEAL) Attest:

ERNEST W. SWIDER DAVID L. LADD Attesting Officer I Commissioner of Patents 

1. A SOLUTION FOR SPINNING ARTIFICIAL FILAMENTS COMPRISING A POLYMER OF THE GROUP CONSISTING OF POLYACRYLONITRILE AND COPOLYMERS OF ACRYLONITRILE CONTAINING AT LEAST 85% BY WEIGHT OF ACRYLONITRILE AND ANOTHER MONOMER SELECTED FROM THE GROUP CONSISTING OF METHYL METHACRYLATE, ACRYLIC ACID AMIDES, METHYL ACRYLATE, VINYL PYRIDINE AND VINYL CARBAZOLE DISSOLVED IN A MIXTURE OF ABOUT 60 TO 95 PERCENT BY WEIGHT OF GLYCOLIC ACID NITRILE AND ABOUT 40 TO 5 PERCENT BY WEIGHT OF ETHYLENE CHLOROHYDRIN. 